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1
Global Needs and Developments in Urban Sanitation |
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By early in the twenty-first century, more than half of the world's population are predicted to be living in urban areas. By the year 2025 that proportion could rise to 60 per cent, comprising some 5 billion people. This rapid urban population growth is putting, and will continue to put, severe strains on the water supply and sanitation services in most major conurbations, especially those in developing countries. In certain major cities in Africa, for example, it is estimated that as many as two-thirds of the population are without adequate sanitation (Water Solidarity Network, 1994). This proportion is unlikely to reduce in the short-term as the peri-urbanization process, in which settlement precedes installation of basic services, is likely to be the dominant influence on urban growth for many years to come. |
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Inadequate water supplies alone will preclude the possibility of reliable, conventional, sewerage systems for many cities. Sewers can rapidly block if water is shut off for periods. It has been calculated that communities with waterborne sewerage normally require more than 75 litres per caput per day (lcd), compared with less than 20 lcd used in many squatter settlements (Cairncross and Feachem, 1993). Alternative sewerage technologies will increasingly be needed on grounds of water availability, construction skills and sustainability, as well as cost. |
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